Tar and Gravel Roofing for New Mexico Homes — Repair, Replacement, and Upgrade Options

What Is Tar and Gravel Roofing?

Built-up roofing (BUR), commonly called tar and gravel, is a multi-ply system consisting of alternating layers of bitumen (asphalt or coal-tar pitch) and reinforcing felt or fiberglass ply sheets, topped with flood-coated bitumen and a ballast layer of gravel. A properly installed BUR system is inherently redundant — water has to penetrate multiple layers before reaching the deck — and a well-maintained roof in New Mexico's relatively dry climate can last 20–30 years.

The main drawbacks: BUR is heavy, requires torch or hot-mop equipment to install and repair, and becomes brittle over time in New Mexico's high-UV, high-temperature environment. Once granule loss begins and the surface bitumen oxidizes, water infiltration accelerates quickly.

Common Repairs for Tar-and-Gravel Roofs

• Blister repair. BUR blisters form when moisture trapped between plies turns to vapor under summer heat. Small blisters under 12 inches can be cut, dried, reseated, and patched. Larger or interconnected blisters usually mean the ply has delaminated and a larger section needs replacement.
• Crack and alligatoring repair. Oxidized bitumen develops a cracked, alligator-skin pattern. Surface cracks can be filled with elastomeric coating, but deep cracking through multiple plies requires cutting out the section and installing new ply material.
• Flashing re-termination. Parapet wall flashing, canale bases, and penetration flashings are the most common entry point for water in an otherwise sound BUR field. Re-terminating the counter-flashing and reseating the base flashing extends the life of the roof significantly.
• Re-graveling thin sections. Wind and rain wash gravel off low-slope roofs over time. Thin or bare sections expose the bitumen surface to UV degradation. Adding gravel back to bare areas significantly slows further deterioration.

When to Consider Converting to TPO or Modified Bitumen

If your tar-and-gravel roof is past the 20-year mark, showing widespread alligatoring, or has had multiple repair events in recent years, full tear-off and replacement with a modern single-ply or modified bitumen system is often more cost-effective than continued patching. Here's why:

• TPO (thermoplastic polyolefin) is lighter, heat-weldable at seams, and highly UV-resistant — a significant advantage in Albuquerque's 300+ sunny days per year. GAF EverGuard TPO carries a 15- or 20-year manufacturer warranty when installed by a certified contractor.
• Modified bitumen (SBS or APP) is the modern evolution of BUR — still an asphalt-based system but with polymer modification that dramatically improves flexibility at low temperatures and resistance to cracking. Easier to install and repair than traditional BUR.
• Roof coatings can extend the life of a sound BUR roof by 5–10 years at a fraction of the cost of replacement, provided the underlying membrane and deck are still structurally sound. We do moisture scanning to determine if a coating is appropriate before recommending it.

What a Tar-and-Gravel Roof Inspection Includes

When we inspect a BUR roof as part of our free roof report, we document:

• Gravel coverage and UV degradation of exposed bitumen surfaces
• Blister count, size, and location
• Flashing condition at all penetrations, parapets, and canale bases
• Drainage patterns and ponding water zones
• Deck soundness (soft spots, delamination evidence)

From that inspection, we give you a clear picture of what's repairable, what has realistic remaining life, and what the cost comparison looks like between continued repair and replacement.

Frequently Asked Questions